Apparatus for laying up adhesive backed sheets

ABSTRACT

A system for laying up multi-layer stacks of sheets is particularly well suited for making pads of notes having ultra-removable adhesive coatings applied in a narrow strip to the back of each sheet. Large sheets having areas many multiples larger than the size of the individual pads, are applied from a continuous paper web having zone coated adhesive strips applied thereto onto a series of recirculating pallets each of which serially receives a large sheet. The web is applied by pressing the adhesive coated side onto the pallet as the pallet travels through a nip formed by the web carrying roll. Closely spaced end-to-end register of the pallets is maintained through the web-applying nip roll and a perforating blade cooperates therewith to form a weakened tear line across the width of the web which is synchronized to coincide with the gap between adjacent pallets. A severing station downstream of the web applying roll causes rapid displacement of the pallet from the one immediately upstream and severs the web along the tear line, resulting in a large single sheet adhering to each pallet. As the pallets recirculate through the system, multiple layers of sheets are laid upon one another until a desired number of sheets has been attained. The large stacks are subsequently cut along multiple parallel lateral lines, and along longitudinal lines corresponding to the positions of the adhesive zone coats and desired final pad widths, respectively.

This is a continuation of application Ser. No. 747,788, filed Aug. 19,1991, now U.S. Pat. No. 5,209,810.

BACKGROUND OF THE INVENTION

The present invention relates to the formation of multi-layer stacks ofsheets and, more particularly, to the formation of stacks ofadhesive-backed sheets of paper to form note pads or the like.

Apparatus and methods for laying up stacks of sheets of paper toultimately form note pads, writing pads, books, or the like are wellknown in the art. Oftentimes the sheets are bound together along oneedge of the stack by an adhesive coating such that individual sheets maybe torn from the pad. The lay up of stacks of sheets of paper prior tothe application of an adhesive to bind one edge of the stack is arelatively simple and straightforward operation.

In recent years, the development of ultra-removable adhesives has led tothe innovation of adhesive-backed notes or sheets in pad form which maybe individually removed and subsequently repeatedly applied and removedfrom other surfaces. The low tack, ultra-removable adhesives aretypically applied in a thin strip on one side adjacent the edge of eachsheet in the stack. However, the presence of the adhesive coatinginterferes with uniform stacking of sheets using conventional sheetstacking methods and apparatus. This has required the development ofalternate systems which must be substantially more complex toaccommodate the adhesive layer on one side of the sheet which inhibitsvirtually any sliding movement between sheets as they are stacked.

It would be desirable to have a system which is capable of assemblingstacks of multi-layer sheets which are coated on one side with a tackyadhesive in a manner which retains good sheet alignment and is capableof high volume production.

SUMMARY OF THE INVENTION

The present invention is directed to a system for laying up stacks ofsheets coated on one side with an adhesive, such as a low tackultra-removable adhesive, to provide pads or tablets of easily removableand reattachable notes. The system is capable of laying up relativelylarge sheets having multiple zone coated adhesive strips on one sidewhich, after multi-layer lay up, may be cut by conventional means into avery large number of small individual note pads.

In its most basic embodiment, the system includes means for circulatingsheet-receiving backing members serially in multiple lay-up cyclesthrough a sheet lay-up station to receive on each member an initiallayer and successive layers of sheets; means for preparing and feeding acontinuous web of sheets into the lay-up station; application means inthe lay-up station for applying the initial layer and successive layersfrom the web to the backing members and the immediately preceding one ofeach successive layer; and, means for separating each applied layer fromthe continuous web.

The system also includes means upstream of the web feeding means forapplying a continuous adhesive coating to at least a portion of one sideof the web. Preferably, the system also includes means upstream of theadhesive applying means for applying a primer coating to at least thatportion of the web to which the adhesive coating is subsequentlyapplied.

The circulating backing members preferably comprise a series of flatpallets and the circulating means includes a series of interrelatedpallet conveyors. The pallet conveyors operate to circulate the palletsin a manner to maintain precise register of the pallets longitudinallyand laterally with respect to the web application means.

The application means includes an upper web-carrying roll which isdisposed above the backing member entering the lay-up station and isoperable to carry the web in the direction of movement of the backingmember through the station, and means for moving the web-carrying rollvertically to bring the portions of the web comprising the initial andsuccessive layers into respective contact with one of said backingmembers and each of said immediately preceding layers carried on saidbacking member. The lay-up station also includes perforating means forproviding a transverse tear line in the web between each seriallyapplied layer.

The web separating means includes severing means on the circulatingmeans downstream of the web-carrying roll for displacing the backingmember and attached layers in the direction of backing member movementrelative to the next following upstream backing member to sever the webalong the tear line.

This system also includes guide means to effect longitudinal alignmentand end-to-end register between each backing member entering the lay-upstation and the immediately following upstream backing member. The guidemeans preferably includes an infeed conveyor with means for aligningeach backing member on the longitudinal centerline of the lay-up stationand for feeding the backing member into the application means, and aretarding conveyor positioned on the centerline and adapted to receivethe backing member from the infeed conveyor to engage the leading edgeof the backing member and the member immediately following it to provideand hold a selected spacing between consecutive backing members. Theinfeed conveyor preferably comprises a lateral side guide which isdisposed parallel to the centerline of the lay-up station and positionedto be engaged by one lateral edge of each backing member, and a firstlive roller conveyor positioned to convey each backing member in adirection which is skewed with respect to the centerline and intoengagement with the lateral side guide.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side elevation view of the system of the present invention.

FIG. 2 is an enlarged top plan view of a portion of the system shown inFIG. 1.

FIG. 3 is a sectional view taken on line 3--3 of FIG. 2.

FIG. 4 is a sectional view taken on line 4--4 of FIG. 2.

FIG. 5 is an enlarged detail of a portion of FIG. 1.

FIG. 6 is an enlarged detail of a portion of FIG. 2.

FIG. 7 is a bottom plan view of part of a multi-layer stack of sheetsassembled in the system of the present invention.

FIG. 8 is a sectional view taken on line 8--8 of FIG. 7.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIGS. 1 and 2, a series of backing members, preferablycomprising flat relatively rigid pallets 10, are circulated in series ona multi-component conveyor system 11 through a lay-up station 12 where acontinuous paper web 13 having a patterned adhesive coating on one sideis applied serially and in successive layers on the pallets. An infeedstation 14 upstream of the lay-up station aligns the incoming pallets 10on the centerline thereof and positions each longitudinally adjacentpair of pallets in precise end-to-end spacing. With the pallets 10entering the lay-up station 12 in longitudinal alignment and end-to-endregister, the web 13 is applied continuously to the serially conveyedpallets. A separating station 15 downstream of the lay-up station 12causes the pallet leaving the lay-up station to be displaced in thedirection of movement relative to the next following upstream pallet tosever the web into an individual sheet forming one layer of the stackbeing laid on the pallet 10. The conveyor system 11 circulates thepallets 10 to cause each one to continuously re-enter the lay-up station12 in the same orientation for successive application of theadhesive-coated web which is again subsequently severed in theseparating station 15.

The paper web 13 is supplied from one or more rolls 16 of any desiredwidth, such as 4 feet (122 cm). The web 13 from the selected roll 16A isfed through a splicer 17 which is operable when needed to splice thelead end of the web from new roll 16B to the tail end of the web fromroll 16A. The paper web 13 is fed directly from the splicer into atake-up mechanism 21 which may include one or more dancer rolls 22 fromwhich it passes through a primer coat applicator 18 designed to apply aseries of laterally spaced and longitudinally continuous zone coats 20of primer (see FIG. 7). If desired, of course, one entire side of thepaper web could be coated with the primer. From the primer coatapplicator 18, the web passes through an adhesive coat applicator 23.The adhesive applicator applies a continuous adhesive zone coat 24 overeach previously applied primer coat 20. The adhesive preferablycomprises a low tack ultra-removable type made of inherently tackypolymeric microspheres which is applied over the underlying primer coat20. The microsphere based adhesive retains its tackiness for repeatedapplication to and removal from various flat surfaces and therepeatability of use is retained by the affinity of the microspheres tothe primer coat, all in a manner well known in the art. From theadhesive coat applicator 23, the web travels through a suitable dryer 25from which it continues into the lay-up station 12. The web 13 entersthe lay-up station 12 with the primer and adhesive zone coats 20 and 24on the underside facing downwardly.

The lay-up station 12 includes means for applying the web initially tothe upper surface of each of the serially circulating pallets 10 and,subsequently, in successive layers over each preceding layer. Eachpallet may comprise, for example, a 4 foot by 8 foot (122 cm × 244 cm)plywood sheet 26 to the upper surface of which is secured a thin layer27 of plastic or other suitable protective material. Preferably, a 4foot by 8 foot (122 cm × 244 cm) backing sheet is placed and temporarilysecured with a low tack adhesive over the top surface of the palletprior to lay-up of the paper web 13. In the preferred application of thelay-up system, the backing sheet 29 provides note pads with a bottomsheet to which the first or lowermost removable sheet in the pad isadhered. Alternately, the backing sheet may be applied to the bottom ofthe multi-layer stack after completion of the lay-up process. The web 13initially passes around an idler takeup roller 28 from which it passesaround a driven upper web-carrying nip roll 30. Immediately afterinitial startup and until the adhesive coating process is operatingproperly and the system is synchronized, the web 13 is drawn from theupper nip roll 30 by a rewind apparatus 31 where it accumulates on arewind roll 32. The upper web-carrying nip roll 30 is carried on avertically adjustable mounting bracket 33 enabling the roll 30 to bemoved toward and away from the circulating pallets 10. In the rewindmode, the mounting bracket 33 and attached roll 30 are raised verticallyto hold the roll out of contact with the pallets.

Referring particularly to FIGS. 2 and 4, pallets 10 may initially enterthe system at a feed station 34 generally in the direction indicated bythe feed arrow 35. As indicated, the upper surface of each palletpreferably has temporarily affixed to it a backing sheet 29. The palletsare initially received on a first live roller feed conveyor 36 fromwhich they pass onto a first transfer belt conveyor 37 where they areconveyed on a slight decline to an infeed conveyor 38 in the infeedstation 14. The infeed conveyor 38 is also a live roller conveyor,however, the parallel rollers comprising the infeed conveyor 38 aremounted on a skew with respect to the longitudinal centerline of theinfeed station 14 and lay-up station 12. The skewed roller infeedconveyor causes the pallets 10 received from the first transfer beltconveyor 37 to be driven against a lateral side guide 40 mounted abovethe infeed conveyor, parallel to the system centerline and positioned tobe engaged by the long lateral edge of each pallet 10 as it moves alongthe infeed conveyor 38. The side guide 40 is located so that the lateraledges of each pallet are parallel to the corresponding lateral edges ofthe web 13 as the pallets enter the lay-up station 12. It is desirableto align the pallets laterally with the web so that the web is laid justslightly inboard of the lateral edges of the pallets to protect theedges of the sheet layers from damage.

To provide and maintain end-to-end register of the pallets 10 as theyenter and travel through the lay-up station 12, a retarding conveyor 41extends from the downstream end of the infeed conveyor 38, under theupper nip roll 30, and through the lay-up station 12 on the longitudinalcenterline of the pallets and the web. The retarding conveyor includes aconveyor chain 42 which carries one or more dogs 43 (see FIG. 5) adaptedto engage a notch 44 in the leading edge of each pallet 10. Theretarding conveyor 41 operates at a speed slightly less than the speedof the infeed conveyor 38 such that the latter causes the pallets tooverrun the retarding conveyor 41 until the notch 44 in the forward edgeof the pallet engages a dog 43. With a pallet construction having anominal 8-foot length, the dogs 43 may be spaced at precisely 96 inchesand the actual length of the pallets would be accurately set at, forexample, 1/8th inch (3 mm) less or at 957/8 inches (243.7 cm). In thiscase, the retarding conveyor 41 will maintain precise end-to-endregister between the pallets in the form of an accurate 1/8th inch (3mm) gap.

In the lay-up station 12, directly beneath the upper nip roll 30 is apowered lower nip roll 45 which is split centrally on its axis to allowpassage of the retarding conveyor chain 42 therethrough. The outersurface of the roll 45 extends slightly above the upper edge of theconveyor chain 42 to engage the underside of each pallet 10 and to formwith the upper nip roll 30 a nip for receiving and carrying the palletsand any layers of web material laid thereon. Roll 45 is driven at thesame peripheral speed as upper roll 30.

When the adhesive coated paper web is ready and the pallets 10 arecirculating through the lay-up station 12, tension is increased on therewind apparatus 31 to break the web being wound on the rewind roll 32.Simultaneously, the mounting bracket 33 and attached upper nip roll 30are lowered to bring the roll surface into contact with the leading edgeof a pallet 10 just entering the nip between rolls 30 and 45. Theadhesive coated surface of the web is pressed onto the pallet as thepallet travels through the nip along the full length of the pallet.

Attached to the mounting bracket 33 with the upper nip roll 30 is aknife roll 46. The knife roll 46 rotates in a direction counter to thenip roll 30 and has attached thereto a radially extending knife blade 48which is adapted to perforate without severing the paper web 13 beingcarried on the nip roll 30. The cutting edge of the knife blade 48 isinterrupted with a series of equally spaced nicks along its full lengthacross the width of the web. For example, a 1/8th inch (3 mm) nick maybe provided approximately every 2 inches (51 mm) such that, when theknife blade contacts the web against the surface of the nip roll 30, theweb will be substantially severed, except for a series of 1/8th inch (3mm) connections equally spaced across the width of the web 13. The kniferoll 46 and attached blade 48 are rotatably mounted on a knife rollshaft 50 with a camming apparatus 47 which periodically andsynchronously causes a slight radial outward movement of the knife bladeagainst the web and nip roll 30 to provide a transverse perforated tearline 51 (FIG. 7) in the web which will coincide with the 1/8th inch (3mm) gap between adjacent pallets 10. Although the circumference of theknife roll 46 could be made substantially equal to the length of onepallet, to keep the roll diameter at a more reasonable size, the cammingapparatus 47 preferably operates to extend the blade and perforate theweb every fourth revolution with a knife roll circumference ofapproximately 2 feet (61 cm), i.e. 1/4 the length of the pallet.Obviously, other suitable knife roll diameters could also be used,properly cammed to provide a perforated cut every 8 feet (244 cm). Thecamming apparatus 47 need only provide a very small radial movement tothe knife blade 48, for example, about 0.010 inch (0.25 mm). The bladein essence cuts the paper in the manner of a conventional steel rule diesuch that the blade penetrates the thickness of the sheet and barelytouches the surface of the upper nip roll 50 which is suitably hardened.

The pallets exiting the lay-up station 12 enter the separating station15 comprising essentially a pair of upper and lower separating nip rolls52 and 53, respectively. The separating rolls are initially driven atthe same speed as the lay-up nip rolls 30 and 45 and are spaced withrespect to one another and with respect to rolls 30 and 45 to capturethe leading edge of the pallet 10 and the web layer or layers laidthereon just as the trailing edge of the pallet leaves the nip formed byrolls 30 and 45. Separating rolls 52 and 53 are driven in oppositerotational directions in synchronism and the roll drive is provided witha clutch mechanism to cause a short rapid speed increase, therebyincreasing the tension in the web and causing the same to break alongthe tear line 51 in the gap between the tail end of the pallet and thenext upstream pallet just entering the nip of lay-up rolls 30 and 45.The low tack adhesive holding the web to the bottom backing sheet 29 onthe pallet or to the immediately preceding layer of a previously appliedweb exhibits adequate strength in shear to prevent the sheet fromslipping or being torn from the pallet. After severing, the pallet has asheet with a zone coated layer of adhesive overlying and coextensivewith the surface area of the backing sheet covering the pallet. Eachtime the pallet is circulated through the lay-up and severing stations,another identical layer is applied thereto allowing a multi-layer stackof sheets of any desired thickness to be laid up.

Support for the pallets between the web lay-up rolls 30 and 45 and thedownstream separating rolls 52 and 53 may be provided by a pair of beltconveyors 54 straddling the downstream end of the retarding chainconveyor 41. Belt conveyors 54 could be replaced by idler rollerconveyors as well.

From the separating nip rolls 52 and 53, the pallet and attached sheetsare directed onto a cross-feed conveyor 55 including powered liverollers to effect a right angle movement of the pallet onto a secondtransfer belt conveyor 56 (see also FIG. 3). Transfer belt conveyor 56may be disposed at a slight incline and the pallets leaving the head endthereof are deposited onto a skewed live roll conveyor 57 operatinggenerally in a direction transverse to belt conveyor 56. Preferably, aside guide 58 is disposed over the skewed roll conveyor 57 to allow thepallets carried thereon to be driven against the side guide foralignment. Pallets having a desired number of layers laid thereon mayalso be discharged from the system, either by pulling them manually fromthe conveyor 57 in the direction of discharge arrow 60 or with asuitable mechanical diverter of any convenient type. Pallets which areintended to be recirculated for the lay-up of another layer continueonto an intermediate belt conveyor 61 from which they are transferredonto the feed conveyor 36 for recirculation through the system aspreviously described. As may be seen particularly in FIG. 2, directionalchange of the pallets 10 through the system is always effected by rightangle transfer, thereby always retaining the directional orientation ofthe pallets. Right angle transfer of the pallets 10 may alternately beprovided by powered right angle turns which effectively turn the palletsthrough a full 360° as they traverse the conveyor system 11.

When the multi-layer stack has attained the desired number of sheets,and is ready for discharge from the system on the live roll conveyor 57,the ragged edges of the stack defined by the aligned multiple tear lines51 which slightly overhang both ends of the pallet, may be trimmed andevened by a pair of edge trimmers 62 on opposite sides of the secondtransfer belt conveyor 56. The trimmers 62 may be activatedautomatically or by an operator just prior to manual removal of a palletas previously indicated.

As shown in FIGS. 5 and 6, the leading edge of each pallet 10 may beprovided with a protective metal insert 63, in which insert the notch 44is formed for receipt of the retarding chain dog 43.

In FIGS. 7 and 8, details of the primer and adhesive zone coats 20 and24 are shown. The applicators 18 and 23 for the primer and adhesive,respectively, lay continuous longitudinal strips on the web which arespaced laterally across the web width. Considering, for example, anominal 4 foot by 8 foot (122 cm × 244 cm) pallet having a multi-layerstack of sheets laid thereon, from which it is ultimately desired toproduce 3 inch by 3 inch (7.5 cm × 7.5 cm) note pads 68, the zone coatsmight be applied in the following manner. Centered on a line 3 inches(7.5 cm) in from each lateral edge 64 of the sheet 65, a double widthlongitudinal zone coat of primer 20 is applied. Subsequently, a doublewidth zone coat of adhesive 24 is applied over the primer coat.Simultaneously, identical double width primer and adhesive zone coatsare respectively applied on parallel centerlines at 6 inch (15 cm)intervals across the width of the sheet 65, the last being located 3inches (7.5 cm) from the opposite lateral edge of the stack of sheets65. After the completed stack is removed from the pallet, the stack issheared or otherwise cut along longitudinal slit lines 66 bisecting thedouble width zone coats 20 and 24 and each adjacent 6 inch (15 cm)interval, and lateral slit lines 67, each of which slit lines 66 and 67are at 3 inch (7.5 cm) intervals. The result is 512.3"×3" (7.5 cm × 7.5cm) note pads 68 each sheet 65 of is adhered to the one immediatelybelow by a thin adhesive strip along one edge.

It is contemplated that the system of the present invention may be usedas well to apply single adhesive-backed sheets to various types ofbacking members presented serially into the lay-up station 12. Further,the surfaces of the backing members need not be flat, but could becurved as well. For example, easily removable labels could be seriallyapplied to containers or the like having a curved or cylindrical outersurface. Various modes of carrying out the present invention arecontemplated as being within the scope of the following claimsparticularly pointing out and distinctly claiming the subject matterwhich is regarded as the invention.

I claim:
 1. A system for laying up multi-layer stacks of sheets, eachsheet having an adhesive coating on one side to cause each succeedingsheet in a stack to adhere to the sheet preceding it, said systemcomprising:means for circulating in series sheet receiving backingmembers in multiple lay-up cycles through a sheet lay-up station toserially receive on each member an initial layer and successive layersof sheets forming a stack; means for feeding a continuous web from whichsaid sheets are formed into said lay-up station; web accumulating meansfor initially receiving said web from said lay-up station; applicationmeans in said lay-up station movable from an accumulating position to anapplication position for applying said initial layer and said successivelayers from said web to said backing members and the immediatelypreceding one of each of said successive layers in each stack; means forsimultaneously moving said application means to the application positionand severing the web from said accumulating means; and means forreceiving each backing member from said lay-up station and forseparating each applied layer from said continuous web.
 2. The system asset forth in claim 1 including web perforating means in said lay-upstation for providing a transverse tear line in the web between eachserially applied layer.
 3. The system as set forth in claim 2 whereinsaid separating means comprises means for displacing said backing memberand attached layers in the direction of backing member movement relativeto the next following upstream backing member to break the web alongsaid tear line.
 4. The system as set forth in claim 1 wherein saidapplication means comprises:an upper web-carrying roll disposed abovesaid backing member and operable to carry said web in the direction ofmovement of said members; and, said moving means comprises means formoving said web-carrying roll vertically to bring the portions of saidweb comprising said initial and successive layers into contactrespectively with one of said backing members and each of saidimmediately preceding layers carried on said member.
 5. The system asset forth in claim 4 wherein said web accumulating means comprises arewind roll receiving the web from said web-carrying roll, and said websevering means comprises means for increasing the tension in the webbetween said web-carrying roll and said rewind roll.